Behavior Genetics

, Volume 35, Issue 5, pp 525–534 | Cite as

Large, Consistent Estimates of the Heritability of Cognitive Ability in Two Entire Populations of 11-Year-Old Twins from Scottish Mental Surveys of 1932 and 1947

  • Beben Benyamin
  • Valerie Wilson
  • Lawrence J. Whalley
  • Peter M. Visscher
  • Ian J. Deary

Twin studies provide estimates of genetic and environmental contributions to cognitive ability differences, but could be based on biased samples. Here we report whole-population estimates using twins from unique mental surveys in Scotland. The Scottish Mental Surveys of 1st June 1932 (SMS1932) and 4th June 1947 (SMS1947), respectively, administered the same validated verbal reasoning test to almost everyone born in 1921 or 1936 and attending school in Scotland. There were 572 twin pairs from the SMS1932, and 517 pairs from the SMS1947. Information on zygosity was unavailable. A novel application of a mixture distribution was used to estimate genetic and environmental components of verbal reasoning variation by maximum likelihood. We found consistent heritability (~0.70) and shared environment (~0.21) estimates. The estimates did not change substantially when additional quantitative traits (height and weight) were added in a multivariate analysis. More generally for studies in genetics, the methodological innovation developed here implies that large (national) data collections can provide sufficient information on twin pairs to estimate genetic parameters, even without zygosity.

Key words

Heritability intelligence IQ mixture distribution twins 


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  1. Bartels, M., Rietveld, M. J., Van Baal, J. C., Boomsma, D. I. 2002Heritability of educational achievement in 12-year-olds and the overlap with cognitive abilityTwin Res.5544553CrossRefPubMedGoogle Scholar
  2. Bishop, E. G., Cherny, S. S., Corley, R., Plomin, R., DeFries, J. C., Hewitt, J. K. 2003Development genetic analysis of general cognitive ability from 1 to 12 years in a sample of adoptees, biological siblings, and twinsIntelligence313149CrossRefGoogle Scholar
  3. Bouchard, T. J. 2004Genetic and environmental influences on human psychological differencesCurr. Dir. Psychol. Sci.13140144CrossRefGoogle Scholar
  4. Bouchard, T. J., Lykken, D. T., McGue, M., Segal, N. L., Tellegen, A. 1990Sources of human psychological differences: the Minnesota Study of Twins Reared ApartScience250223228PubMedGoogle Scholar
  5. Bouchard, T. J., McGue, M. 2003Genetic and environmental influences on human psychological differencesJ. Neurobiol.54445CrossRefPubMedGoogle Scholar
  6. Carroll, J. B. 1993Human Cognitive Abilities: A Survey of Factor Analytic StudiesCambridge University PressCambridge, UKGoogle Scholar
  7. Deary, I. J., Whalley, L. J., Lemmon, H., Crawford, J. R., Starr, J. M. 2000The stability of individual differences in mental ability from childhood to old age: follow-up of the 1932 Scottish Mental SurveyIntelligence284955CrossRefGoogle Scholar
  8. Deary, I. J., Whiteman, M. C., Starr, J. M., Whalley, L. J., Fox, H. C. J. 2004The impact of childhood intelligence on later life: following up the Scottish Mental Surveys of 1932 and 1947J. Pers. Soc. Psychol.86130147CrossRefPubMedGoogle Scholar
  9. Gottfredson, L. S., Deary, I. J. 2004Intelligence predicts health and longevity: but why?Curr. Dir. Psychol. Sci.1314CrossRefGoogle Scholar
  10. Gray, J. R., Thompson, P. M. 2004Neurobiology of intelligence: science and ethicsNat. Rev. Neurosci.5471482CrossRefPubMedGoogle Scholar
  11. Health, A. C., Nyholt, D. R., Neuman, R., Madden, P. A. F., Bucholz, K. K., Todd, R. D., Nelson, E. C., Montgomery, G. W., Martin, N. G. 2003Zygosity diagnosis in the absence of genotypic data: an approach using latent class analysisTwin. Res.62226CrossRefPubMedGoogle Scholar
  12. Humphreys, L. G., Davey, T. C., Park, R. K. 1985Longitudinal correlation analysis of standing height and intelligenceChild. Dev.5614651478PubMedGoogle Scholar
  13. Imaizumi, Y. 2003A comparative study of zygotic twinning and triplet rates in eight countries, 1972–1999J. Biosoc. Sci.35287302CrossRefPubMedGoogle Scholar
  14. Johnson, F. W. 1991Biological factors and psychometric intelligence: a reviewGenet. Soc. Gen. Psychol. Monogr.117313357PubMedGoogle Scholar
  15. Joseph, J. 2003The Gene Illusion: Genetic Research in Psychiatry and Psychology Under the MicroscopePCCSRoss-on-Wye, UKGoogle Scholar
  16. Knopik, V. S., DeFries, J. C. 1998A twin study of gender-influenced individual differences in general cognitive abilityIntelligence268189CrossRefGoogle Scholar
  17. Mehrotra, S. N., Maxwell, J. 1949The Intelligence of twins: a comparative study of eleven-year-old twinsPopul. Stud.3295302Google Scholar
  18. Molinari, E., Sartori, A., Ceccarelli, A., Marchi, S. 2002Psychological and emotional development, intellectual capabilities, and body image in short normal childrenJ. Endocrinol. Invest.25321328PubMedGoogle Scholar
  19. Neale, M. C. 2003A finite mixture distribution model for data collected from twinsTwin Res.6235239CrossRefPubMedGoogle Scholar
  20. Neale, M. C., Boker, S. M., Xie, G., Maes, H. H. 2002Mx: Statistical Modelling6Department of PsychiatryRichmond, VAGoogle Scholar
  21. Neale, M. C., Cardon, L. R. 1992Methodology for Genetic Studies of Twins and FamiliesKluwerDordrechtGoogle Scholar
  22. Neisser, U., Boodoo, G., Bouchard, T. J., Boykin, A. W., Brody, N., Ceci, S. J., Halpern, D. F., Loehlin, J. C., Perloff, R., Sternberg, R. J., Urbina, S. 1996Intelligence: knowns and unknownsAm. Psychol.5177101CrossRefGoogle Scholar
  23. Pietilainen, K. H., Kaprio, J., Rissanen, A., Winter, T., Rimpela, A., Viken, R. J., Rose, R. J. 1999Distribution and heritability of BMI in Finnish adolescents aged 16y and 17y: a study of 4884 twins and 2509 singletonsInt. J. Obes. Relat. Metab. Disord.23107115CrossRefPubMedGoogle Scholar
  24. Plomin, R., Spinath, F. 2004Intelligence: genetics, genes, and genomicsJ. Pers. Soc. Psychol.86112129CrossRefPubMedGoogle Scholar
  25. Plomin, R., DeFries, J. C., McClearn, G. E., McGuffin, P. 2001Behavioral Genetics4WorthNew YorkGoogle Scholar
  26. Scarr-Salapatek, S. 1971Race, social class, and IQScience17412851295PubMedGoogle Scholar
  27. Schousboe, K., Visscher, P. M., Erbas, B., Kyvik, K. O., Hopper, J. L., Henriksen, J. E., Heitmann, B. L., Sørensen, T. I. A. 2004Twin study of genetic and environmental influences on adult body size, shape and compositionInt. J. Obes.283948CrossRefGoogle Scholar
  28. Schousboe, K., Willemsen, G., Kyvik, K. O., Mortensen, J., Boomsma, D. I., Cornes, B. K., Davis, C. J., Fagnani, C., Hjelmborg, J., Kaprio, J., Lange, M., Luciano, M., Martin, N. G., Pedersen, N., Pietilainen, K. H., Rissanen, A., Saarni, S., Sørensen, T. I. A., Baal, G. C. M., Harris, J. K. 2003Sex differences in heritability of BMI: a comparative study of results from twin studies in eight countriesTwin Res.6409421CrossRefPubMedGoogle Scholar
  29. Scottish Council for Research in Education1933The Intelligence of Scottish ChildrenUniversity of London PressLondonGoogle Scholar
  30. Scottish Council for Research in Education1949The Trend of Scottish IntelligenceUniversity of London PressLondonGoogle Scholar
  31. Scottish Council for Research in Education1953Social Implications of the 1947 Scottish Mental SurveyUniversity of London PressLondonGoogle Scholar
  32. Silventoinen, K. 2003Determinants of variation in adult body heightJ. Biosoc. Sci.35263285CrossRefPubMedGoogle Scholar
  33. Silventoinen, K., Sammalisto, S., Perola, M., Boomsma, D. I., Cornes, B. K., Davis, C., Dunkel, L., Lange, M., Harris, J. R., Hjelmborg, J. V. B., Luciano, M., Martin, N. G., Mortensen, J., Nistico, L., Pedersen, N. L., Skytthe, A., Spector, T. D., Stazi, M. A., Willemsen, G., Kaprio, J. 2003Heritability of adult body height: A comparative study of twin cohorts in eight countriesTwin Res.6399408CrossRefPubMedGoogle Scholar

Copyright information

© Springer Science+Business Media, Inc. 2005

Authors and Affiliations

  • Beben Benyamin
    • 1
  • Valerie Wilson
    • 2
  • Lawrence J. Whalley
    • 3
  • Peter M. Visscher
    • 1
  • Ian J. Deary
    • 4
  1. 1.School of Biological SciencesUniversity of EdinburghEdinburghUK
  2. 2.Scottish Council for Research in EducationUniversity of GlasgowEdinburghUK
  3. 3.Department of Mental Health, Cornhill Royal HospitalUniversity of AberdeenUK
  4. 4.Department of PsychologyUniversity of EdinburghEdinburghUK

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